Due to this, in the ink discharge processing by the ink jet head 306 shown in FIG. 29(b), ink jet heads 306 for just the three colors R, G, and B are provided in advance, so as to discharge the single colors R, G, and B. And a three color array including R, G, and B or the like is formed upon the single motherboard 301 by using these ink jet heads 306 in order.